Energy Efficient Relay-Assisted Cellular Network Model using Base Station Switching

Cellular network planning strategies have tended to focus on peak traffic scenarios rather than energy efficiency. By exploiting the dynamic nature of traffic load profiles, the prospect for greener communications in cellular access networks is evolving. For example, powering down base stations (BS) and applying cell zooming can significantly reduce energy consumption, with the overriding design priority still being to uphold a minimum quality of service (QoS). Switching off cells completely can lead to both coverage holes and performance degradation in terms of increased outage probability, greater transmit power dissipation in the up and downlinks, and complex interference management, even at low traffic loads. In this paper, a cellular network model is presented where certain BS rather than being turned off, are switched to low-powered relay stations (RS) during zero-to-medium traffic periods. Neighbouring BS still retain all the baseband signal processing and transmit signals to corresponding RS via backhaul connections, under the assumption that the RS covers the whole cell. Experimental results demonstrate the efficacy of this new BS-RS Switching technique from both an energy saving and QoS perspective, in the up and downlinks

Embedded direct numerical simulation for aeronautical CFD

AbstractA method is proposed by which a direct numerical simulation of the compressible Navier-Stokes equations may be embedded within a more general aeronautical CFD code. The method may be applied to any code which solves the Euler equations or the Favre-averaged Navier-Stokes equations. A formal decomposition of the flowfield is used to derive modified equations for use with direct numerical simulation solvers. Some preliminary applications for model flows with transitional separation bubbles are given.</jats:p

Do all institutional investors care about corporate carbon emissions?

This paper investigates whether institutional investors promote the abatement of corporate carbon emissions. Using firm-level data on the U. S from 2007 to 2017, we find that institutional investors help reduce carbon emissions. The result is more pronounced in firms with more independent (investment companies, investment advisors, and pension funds), long-term, and monitoring institutional ownership. Our result holds when we employ a quasi-natural experiment and the difference-in-differences approach to address endogeneity. The channel analysis documents that institutional investors help reduce carbon emissions by reducing energy consumption. We also find that shareholder activism is a proximal monitoring mechanism through which institutional investors influence firms to achieve better carbon performance. Finally, our results show that the advantage for institutional investors from reducing carbon emissions is higher firm value

The Relevant Operators for the Hubbard Hamiltonian with a magnetic field term

The Hubbard Hamiltonian and its variants/generalizations continue to dominate the theoretical modelling of important problems such as high temperature superconductivity. In this note we identify the set of relevant operators for the Hubbard Hamiltonian with a magnetic field term.Comment: 19 pages, RevTe